After running out of windshield wiper fluid, Rick and Morty go to a planet where they learn that the peaceful local populace are preparing for the “Festival”, an annual event where the people are free to commit crimes for one night without consequence, as a way to vent their violent tendencies (an event Rick compares to The Purge
and The Purge: Anarchy
). Rick decides to stay to observe the purge, while Morty is against the entire concept. Morty forces Rick to rescue one of the aliens, a young girl named Arthricia, before she is attacked. However, Arthricia betrays them and steals Rick’s gun and spaceship, leaving Rick and Morty to fend for themselves. Back on Earth, Jerry’s attempts to bond with Summer are interrupted by a call from Rick asking for a beacon to be sent to them. Rick and Morty find a lighthouse to improve the beacon’s signal strength. The peaceful lighthouse owner asks only that Morty listen to “his tale”, a poorly written screenplay. After the reading Morty, who had just listened to the entire script, kills the lighthouse owner, when he is unable to handle Morty’s critique. When the beacon arrives, Rick and Morty receive a pair of advanced power armor suits sent by Summer. Morty goes on a rampage, finally releasing his pent up rage, and killing every alien he sees before finding Arthricia. She pleads with them that she only stole their spaceship to kill the corrupt nobility who implemented the purge system in the first place. Rick knocks out a still angry Morty and helps Arthricia execute the nobles before leaving. However, within seconds of Rick and Morty leaving the planet, rioting breaks out over disagreements about how its new society should be arranged, with one alien calling for everyone’s attention and rehashing the idea of the Festival. When Morty feels guilty over the aliens he’s killed, Rick lies to him that the chemicals in a candy bar he had eaten caused him to go on the rampage, even though the wrapper shows it did not contain the chemical “purgenol”.
Post-Credit Scene: Jerry is forced to admit to Beth that he had wasted all of his money on a paid service where he could talk with another person over the phone. Beth tells Jerry to get a job.